The broad objective of this proposal is to develop a novel, rapid, robust and portable 3He hyperpolarization apparatus that will produce ~ 1 L / hour of 3He gas spin-polarized to 40% or greater. The apparatus will use the metastability-exchange optical pumping method (MEOP), a theoretically-favorable process that has traditionally been difficult to implement. Recent advances in compressor and laser technology have overcome these hurdles. A polarizer based on the MEOP process will provide an almost ten-fold increase in production rate for hyperpolarized 3He when compared to current polarizer technology based on the alternative spinexchange optical-pumping method (SEOP). The proposed apparatus will be the first MEOP 3He hyperpolarization apparatus dedicated to biomedical MRI use in the US and which can be located in the biomedical imaging environment. This multidisciplinary program bridges the physical and biomedical sciences, with the potential to provide significant breakthrough research in pulmonary physiology and medicine. Thus this program qualifies for the R-21 funding mechanism. The Specific Aims of the program are: [unreadable] 1. Design and fabricate a prototype 3He hyperpolarization apparatus that operates using the metastabilityexchange optical pumping (MEOP) method, and produces ~ 1 L per hour of 40% polarized 3He gas. [unreadable] 2. Determine optimum operating conditions for the apparatus, studying 3He polarization signal as a function of operating parameters, including gas mixture, pressure, and compression rate. [unreadable] 3. Perform phantom 3He MRI studies with gas from the MEOP 3He hyperpolarization apparatus. [unreadable] [unreadable] [unreadable] [unreadable]